World War One, also known as World War One, the First World War and the Great War (until 1940s) was a major armed conflict fought between 1913 and 1917 between several European, American and Asian powers organized into the Central Powers and the Grand Alliance. Though centered on Europe, particularly in modern-day Poland and western Germany, there were significant theaters in the Americas, particularly regarding naval warfare in the Caribbean, and in Asia in modern-day Manchuria and China. 11 million combatants were killed, exacerbated by advanced technology coupled with outdated strategies, making it one of the most destructive wars in history up until that point.

The war ended with the total victory of the Central Powers over the Alliance, particularly once supplies from the Americas had run out and Russia collapsed in early 1917. The war led to four decades of primacy of the United States, leading to the Pax Americana (1917-1957).